The Queen's formal consent to the marriage was unveiled Thursday, which happens to be her 85th birthday. Under the Great Seal of the Realm, she signed an elaborate notice of approval that proclaimed, in transcribed calligraphy, consent to the union of "Our Most Dearly Beloved Grandson Prince William Arthur Philip Louis of Wales, K.G., and Our Trusty and Well-Beloved Catherine Elizabeth Middleton."

The Queen declared her approval and signed the lavish document – officially called the Instrument of Consent – on Feb. 9, but it was only made public Thursday.

Grandsons rarely need a grandmother's approval to marry. But in William's case, there's a little something called the Royal Marriages Act of 1772 to worry about. It requires the sitting monarch to formally approve the marriages of most direct descendants of King George II.

The Instrument of Consent was drafted by the Crown Office and hand-written and illuminated on vellum by one of a panel of scrivener/artists. It will be given to the couple after they are married.